Abstract: The explanation of the apparent image of an underwater object is a topic which seems simple but is often confusing and mistaken.The systematic study and simulations have been made on this problem.The results have corrected some popular mistakes about this matter,and indicated that generally the apparent position,size and shape of the image of an underwater object will change under different conditions,and this change is often beyond one＇s intuitional expectation.This work has also provided an excellent example for developing the learners＇ ability of creative thinking and solving practical problems.

Key words: light refraction, geometric optics, apparent image, underwater objects